Antenna structure



FIG. 1 is a perspective view of an antenna structure showing our new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side elevation view thereof, the left side elevation view being a mirror image thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for an antenna structure, as shown and described. 